The surfacing of wheels and rollers with a nonuniform cross section leads to surface heating. Subsequent surface cooling produces stress and potentially disintegration of the component. To prevent such problems, heating of the disk and rim during surfacing is proposed, so that the temperature difference over the component is no more than 100°C.

TA technique for construction of an experimental hardening curve based on the experience of compression of cylindrical specimens made of 11YuA steel is presented. The upsetting of specimens with 9 mm high and 5 mm in diameter was carried out on a R-5 testing machine with the recording of the “load-displacement” diagram. To reduce the influence of friction forces between the upset workpiece and the tool, the experiment was completed when the ratio of height to its diameter was equal to 1. This leads to a limitation of the range of the resulting strain intensity within 0.35 ... 0.45. To expand the boundaries of constructing the hardening curve, two composite samples obtained after the first upset were deformed, which made it possible to achieve a strain intensity of 0.75 ... 0.85 in each sample. Since the sample was compressed with the constant rate, the “load-displacement” graph was divided into several intervals, in which, in accordance with the displacement of the pressure plate, the cross-sectional area of the sample, deformation, load, and the corresponding stresses were determined. The set of obtained values of strain and stress intensities made it possible to plot the hardening curve of the studied material with subsequent approximation by a linear function. Hardening curves show that the nature of hardening of the material under study does not change as a result of a compressive test of a composite sample, therefore, contact friction forces do not affect the power parameters at significant strain rates. The proposed compression test method using a composite sample can significantly reduce the complexity of constructing a hardening curve and significantly expand the range of uniform deformation under uniaxial stress conditions.The work was carried out within the framework of the RFBR grant No. 20-08-00401 A.

The tendency of economically alloyed and high-chromium steel coatings to crack is compared, along with their wear resistance in various conditions. To slow the wear of the working surfaces, the selection of the hard coating employed in surfacing should take account of the expected operating conditions.

Anomalous failure of 75ХМ roller steel in plasma quenching is analyzed. Its microstructure is studied. Recommendations are made for its prevention.

Final restoration of slide valves in lubrication stations by ultrasonic surface plastic deformation and carbonitriding is considered.

The influence of carbonitration on the magnetic properties, hardness, and wear resistance of unalloyed electrical steel grade 10 895 was investigated. It was found that carbonitration increased the surface hardness from HV = 140 to 580. This is not as important as when applying borides and nickel borides (HV 2015) but is still very significant (4.1-fold), with a 90% increase in the wear resistance being achieved with friction on the Ferodo disk. Due to the improvement of the magnetic properties of steel, the torque of the magnetic clutch MWU increased by 40%.

The wear resistance of a deposited layer made of experimental 40Cr16MnSi chromium wire was experimentally investigated. The work was carried out by comparing the wear of 65Mn steel with cladding and without it via the friction and wear based on two schemes of tribological laboratory tests without lubrication and cooling of the material. The first simulated the conditions of adhesion-fatigue wear, while the second simulated an abrasive. It is shown that the alloying of the filler wire with manganese and silicon made it possible to eliminate the formation of pores in the deposited layer during surfacing in protective gases. A high content of chromium provides uniformity of the microstructure, high hardness and, accordingly, wear resistance. It has been established that the formation of the martensitic structure initially has high hardness (~58 HRC) and a reserve for an increase under mechanical stress (~1.3 times). Surfacing with 40Cr16MnSi wire instead of the “sormayt” alloy type on the tops of screws helped to reduce the complexity and cost of recovery of products that provide a comparable resource. These results allow us to consider the 40Cr16MnSi experimental wire as a promising wear-resistant material for the restoration of machine parts and mechanisms.

The results of studying changes in the strength properties of the surface of a tool product from high-speed steel (HSS) of the W6Mo5Cr4V2 type after its hardening by the application of the Si−O−C−N micron plasma coating system are presented. The study is conducted by comparing the properties of the surface, evaluated by the same methods before and after coating. In this case, the sample goes through a complete cycle of mechanical and heat treatment designed for the product before coating. The results of evaluation of the adhesive strength of the coating using the proposed method of recalculation are given, and the correspondence between the index of destruction of the coating of the VDI 3198: 1992-08 technique and the delamination coefficient is obtained. The study itself is carried out by indenting and scratching the surface with HV, HRC and HRB-type indenters in the load variation range of 0.1–200 N, which makes it possible to simulate different levels of contact pressure in the surface layer of the substrate and at the base–coating interface. It is shown that the application of a thin-film coating of the Si−O−C−N system by the plasma method makes it possible, in addition to standard heat treatment of HSS steel, to increase the surface resistance to penetration and scratching with harder bodies. The causes of the obtained positive effect are analyzed and the limits of the expediency of applying plasma hardening depending on the contact task are described. These results make it possible to consider the method of the additional plasma hardening of HSS steel as promising for implementation.

In this paper, we studied the wear of a plasma thin-film coating (PTFC) of the Si–O–N–C system deposited on high-speed steel of the W6Mo5Cr4V2 type. The tests were performed using a friction machine according to the “disk-indenter” scheme under dry friction conditions by the adhesive and abrasive wear mechanism. A steel indenter was used to simulate adhesive wear and a corundum indenter was employed to simulate abrasive wear. The positive effect of the coating on the wear resistance of the sample surface was established. The obtained positive effect has been shown to be achieved as a result of a combination of four factors: high coating hardness, phase hardening of the base material, reduction of surface roughness, and partial prevention of adhesion bonding of contacting bodies. Within the depth of the material hardening zone formed upon the PTFC deposition, the wear resistance of W6Mo5Cr4V2 steel was shown to increase by 3.2 times when paired with a steel indenter and 2.4 times when paired with a corundum indenter. We concluded that a PTFC thickness of 0.8–1 μm is sufficient to increase the wear resistance of high-speed steel products and to provide an acceptable level of coating adhesion.

Liquid nitriding (carbonitriding) effect on hardness, wear resistance and magnetic properties of electric steel grade 10 is reviewed here, as well as on the electric contact resistance. It was found that hot-rolled steel 10 loses its hardness as a result of annealing. Surface carbonitriding of specimens generates an improved layer of higher hardness, high wear resistance and increased electrical resistance. The specimens carbonitrided have contact electric resistance higher than that of hot-rolled specimens after descaling. The magnetic permeability of ‘grade 10’ steel does not practically change after annealing and carbonitriding, while the magnetic permeability corresponds to the magnetic field strength in a very typical way with typical parameters for carbon steels. Traditional methods of processing electrical steels, carried out in order to achieve such a complex effect, combine heterogeneous processes, such as electroplating, vacuum, plasma, high - temperature annealing, coating-are very expensive and difficult to implement. Carbonitration is more accessible for practical use and has a significantly lower cost. The results obtained can be used in the design of magnetic circuits for various electric devices.

Laser and plasma hardening practically do not damage the surface, so the parts after their execution are sent to the assembly without finishing machining, which reduces the complexity and logistics of the process. In conditions of dry friction hardened steel discs 45 and 40Kh increase wear resistance up to 100 times. The service life of parts strengthened by laser and plasma hardening is repeatedly increased. Laser hardening differs from plasma hardening by higher cost of equipment, therefore it is preferable in large-scale production. Plasma installation UDGZ-200, thanks to manual operation, it is possible to temper the surfaces inaccessible or inaccessible to other hardening methods. This, together with the low cost of equipment, makes plasma hardening cost-effective in conditions of single-unit and small-scale productions.

The properties of 65 G steel used in the manufacture of elements of soil-cultivating machines, strengthened by plasma quenching through the use of the UDGZ-200 serial installation, without water cooling, are studied. It is established that quenching leaves on the surface bands of the heat tints. Surface roughness varies from Ra 0.3 to Ra 2.6 as a result of hardening. When quenching a plate 30 mm thick, the cooling rates in the region of pearlite decomposition of austenite (750 … 500 °C) are in the range of 50–100 °C/s, which allows the supercooled austenite to be maintained until the martensitic transformation begins (270°C). In this case, quenching condition is provided. At temperatures below the martensitic transformation, the cooling rates slow down, which a factor is contributing to the prevention of cracking during quenching. As a result of reducing the arc movement speed from 33 to 24 and up to 14 m/h, occurs an increase in the hardening depth with the boundary of HV500 450 from 0.25 up to 0,35 and 0,50 mm and an increase in the width of the hardened strip from 9 to 11 and to 13 mm, respectively. Reducing the thickness of the plate from 30 to 10 mm is accompanied by an increase in the depth of hardening to 1.9 mm. The wear resistance of normalized 65 G steel as a result of plasma quenching by steel indenter friction (ShX-15) is increased by 4 times. When rubbing with corundum indenter, the wear resistance of the hardened steel is 15.3 times higher than in the case of friction with a steel indenter. This makes plasma hardening promising for strengthening elements of soil-cultivating machines in which wear conditions are closer to tests by a corundumindenter.

For the example of 5ХНМ steel, we show that plasma quenching prior to carbonitriding significantly increases the hardness and thickness of the carbonitride layer. Little change is seen in the parameters of the heterogeneous transition zone.

The microstructure, hardness, and wear resistance of surface deposited layers made of experimental 20Cr16 and 26Cr16 wires on 55Mn steel were investigated. It was shown that during crystallization, these deposited layers, having very high hardness, did not form cracks and/or other defects typical of high-strength deposits. The absence of dendrites and lack of significant chemical composition gradients across the overall section ensures that they are microstructurally uniform in depth, and therefore, their hardness and wear resistance is also independent of layer depth. The latter properties appeared to be only slightly dependent on the type of wires used, despite their significant difference in carbon content. The results make it possible to consider the designed experimental wires as highly promising for practical application in industry.

Plasma hardening by a standard UDGZ-200 unit makes it possible to provide not only a marked increase in steel 20Kh13 hardness and wear resistance, but also an improvement of corrosion resistance. Under experimental conditions, the corrosion resistance of steel 20Kh13 after hardening increased by a factor of 1.86, but decreased somewhat (by 15%) in the transition area to unhardened metal.

The nature of wear of an imported QWS2250 pump plunger coated with a Colmonoy type protective layer is studied. Taking account of the data obtained economic import substitution technology is developed for surfacing plungers with chromium steel. Modification of surfacing wire with chromium, boron, and titanium provides the possibility of performing surfacing in a protective gas, and obtaining uniform surfacing layer hardness and good wear resistance.